Carburetor for internal-combustion engines



F. E. BALDWIN. CARBURETOR FOR INTERNAL COMBUSTION ENGINES- V APPLICATION FILED DEC; 30, I920. 1,435,578. Patented Nov. 14, 1922.

2 SHEETS*SHEE1 I llllllllllllilililii F. E. BALDWIN.

CARBURETOR. FOR INTERNAL COMBUSTION ENGINES.

' APPLICATION FILED DEC. 30. mm.

1,435,578. Patented Nov. 14, 1922.

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z I A 2 X5 0 22 I Q IIIIIITIWIIIIII IIII j W n roe lvmvts a-q Fmafl EEQ/dwzh l it .t'a til. fizf ilg o FREDERIC BALDWIII, OF PHILADELPHIA. PENNSYLVANIA.

CARBURETOR FOR INTERNAL-COIVIEUSTION ENGINES.

Application filed December 30, 1920. Serial No. 434,051.

To aZZ whom it may concern:

Be it known that I, F nnnnnro E. BALD- WIN, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have in vented certain new and useful Improvements in Carburetors for Internal-Combustion Engines, of which the following is a specification.

In carburetors having a fixed air entrance, and but one fuel inlet, the explosive mixture tends to become too rich in fuel as the speed of the engine increases.

The object of this invention is to overcome this difficulty and to produce a carburetor which will furnish a more nearly constant proportion of fuel to air at all speeds of the engine than is possible with the type of carburetor above referred to.

For this purpose I ai'lniit air continually to the fuel passage between a restriction in the passage and its orifice and I admit this through a calibrated orifice provided 1gb the wall of the fuel passage and the ration of this orifice determines the amount of air admitted, and therefore the calibrated orifice is small, so small that if arranged to be exposed to the grease and dust surrounding the engine, it would readily, and in use'surely, be stopped thereby, but the location of this calibrated orifice in the wall of the fuel passage and inside of the carburetor where it is scoured by gasoline avoids that objection and insures successful operation. This admission of air tends to reduce the suction acting on the fuel outlet at said restriction, so that it is less than it would be if such air were not admitted. Therefore, with increasing vacuum, there is less fuel, proportionately, mixing with the air entering through the fixed air entrance, thus the over-enrichment of the mixture at increase of speed is pre vented.

The calibration of the fuel and air inlet-s in any case is difficult and in some cases it amounts to almost a commercial in'ipossibility, and if accomplished to suit certain condit-ions of use it might be unsuited for other conditions of use. Moreover, changes of temperature do not aflect the viscosity of air and gasoline or other hydrocarbon fuel in the same way. To overcome these ditficub ties and enable a change to be made in the relative size of the fuel and air inlets i make the restriction in the fuel inlet adjustable by the provision of a needle valve cooperating therewith. 1 place the air inlet orifice at or near the base of the fuel nozzle and I calibrate this orifice to the suitable size for the engine. This orifice is extremely small, so small 1n fact that were it located on the outside of the carburetor, as has been always heretofore attempted, the grease and dust round the engine would soon close it up and make it inoperative. By locating it in the fuel nozzle itis kept clear by the flow of fuel so that it never becomes clogged and is always operative. this orifice I may say that I find the size for a Ford engine having 177 cu. in. piston displacement to be for from 6 to 8' 1/1000 of an inch, for an engine having 360 cu. in. in piston displacement I find an orifice of 18/1000 too large, 14/1000 1 find about correct. This orifice is so small that it will not permit an initial How of fuel therethrough which is suflicient to prime the engine with which the carburetor is associated when said engine is started.

Two forms of construction embodying this invention are illustrated in the annexed drawings in which- Figure l is a yertical section on the line 1-1 of Figure 2, the float chamber being shown in elevation.

Figure 2 is a horizontal section on the line 2-2 of Figure 1.

Figure 3- is a vertical section through a modified form of the invention, certain parts being shown in elevation.

Figure 4 is a horizontal section on the line H of Figure 3.

Referring to Figures 1 and 3, air enters the carburetor through the air entrance 1 is the fuel supply passage connecting through passage 15. with the float chamber 9 which is of the usual type and maintains the fuel level at a point below the outlet of the fuel nozzle in the usual manner.

An idling supply tube is shown at 10 for supplying a mixture for idling through pas- To illustrate the size of sage l7 slightly above the throttle valve 2.

Air is admitted to the space above the tube 10 through the orifice 25. to form such idling mixture.

The air inlet to admit air to the fuel nozzle is shown at '3 to which air is admitted through the air passage ,0. A restriction shown as a needle valve 22 is placed so to co-operate with the fuel'passages l and and to retard the flow of fuel through said passages 1 and 15.1 The diameter of the fuel passage 1 is larger in area than necessary to admit sufficient fuel to meet the requirement of the engine, and an emulsion is formed within the, said passage by the mixture of the fuel and air admitted at 3. Owing to the admission of air at orifice 3, the suction at the outlet at valve 22 does not increase as rapidly as does the suction at the nozzle outlet, and consequently the increase in fuel flow on increased suction is not as great as if the fuel stood in a solid column in the nozzle 1 up to the outlet thereof. In the drawings the outlet of the fuel passage 15 is shown controlled by a a needle valve 22 which is adjustable to change the size of the said outlet to suit different conditions of operation.

Between the valve 22 and the outlet of the fuel nozzle is located the air inlet or passage 3 in direct communication with the atmosphere through air passage 6. The air passage 6 extends sufficiently above the level of the fuel in the float chamber to prevent the overflow of fuel at all times. The air passage 6 extends to the exterior of the carburetor, but its cross sectional area is much larger than the area of the inlet 3 and so large that it is not stopped by dirt and grease. To distinguish this device from some other devices feeding air to a fuel passage, I wish to draw attention to the fact that this device feeds air to the fuel passage as soon after the fuel passage commences to function as the fuel standing in the passage 6 is drawn out of theinozzle, and that air continues to be fed in more or less quantity during the time the device is in operation.

At no time except immediately after start ing does the air passage feed fuel, or air and fuel mixed, nor does it form any part of the fuel supply.

Figure 2 shows another form of construction where the air enters through the orifice 6", passes down passage 31 formed between the wall 30 of the carburetor and the idling supply tube 8, and through passage 32 to the air inlet 3 An outer shell or housing 5 is placed around the fuel nozzle 1 to prevent the fuel flowing from the nozzle 1 through air orifice 3 when the engine is at rest. The

wall 5 forms a tight joint where it engages;

the outer surface of nozzle 1 at the upper end thereof, so that no air can pass through the space between said wall and the nozzle. Fuel is fed from the float chamber 9 through .thepassage 15, past the needle valve 22 into-[the nozzle tube 1 where it is mixed with air flowing into said nozzle tub-2 through orifice 3 to form an emulsion as heretofore described.

Fuel is drawn through the tube 10 for idling, said fuel being mixed with air admitted through port 25 and the resultant mixture is drawn through the port l7 into the intake passage in the same manner as in the device shown in Fig. 1".

The operation may be described as follows: The vacuum in the carburetor produces a suction at the fuel outlet adjacent the valve 22. Suction is also exerted at the air inlet 3, causing the air to enter the n0z-' flow and a mixture of substantially'constant proportions is produced. I

This admitting of air movin at high speed to the fuel duct'at high v.e ocity (the lowest vacuum used in this device being about five inches of water column at 400 R. P; M. and raising to about seventy inch water column at 2000 R. P. M.) has another advantage in that it tends to aerate or atomize all the fuel before it leaves the fuel passage, in which form it mingles more readily with the incoming air than when, in the usual form, of a solid stream, thus producing a fuel more thoroughly mixed with the air than is usually the case. Furthermore exhaustive tests have proven that this aerating of the fuel in the fuel duct itself enables a lower grade of fuel to be used with thorough satisfaction and without any annoyance or disadvantage. In the described construction, the needle valve has a double function. It not only controls the flow of fuel but also regulates the percentage of air admitted to the interior of the fuel passage.

The difference in the percentage of air delivered to the fuel duct is controlled as follows: With a given position 0 the needle valve and at a given, speed of t e engine, a

certain air to fuel ratio is obtained in the fuel duct. Closing the needle valve slightly retards the flow of fuel with consequent increased How of air and thus the air to fuel ratio increases. Byv opening the needle valve the action is reversed and'the air to fuel ratio diminishes. Consequently, it is a simple matter toobtain the exact air to fuel ratio re uired. Without a needle valve both air and uel orifices would requiresuch close calibration that it would be commercially impracticable to obtain the satisfactory air fuel ratio.

Furthermore owing to the difference in viscosity of the two fluids the flow .of the fuel is more affect-ed by temperature changes than the flow of the air. So thatwith a sudden drop in temperature the fuel would flow more slowly, thus making the mixture too thin and this reduction in flow of fuel will at the same time by increasing the suction at the air entrance increase the flow of air,,further reducing the flow of fuel and making the amount of fuel still less, so that the amount of fuel will not be sullicient to operatethe engine properly. However the needle valve affords means for preventing or correcting this action. With calibrated orifices the correct relative proportion of air and. fuel could only be obtained by a long series of experiments, Whereas with a needle valve only a slight adjustment gives the correct proportion at once.

Obviously modifications may be made in details of construction and arrangement without departing from the spiritof the invention which is not limited as to such mat-' air inlet orifice of fixed area provided through the wall of the fuel nozzle and located adjacent the base of said nozzle and between the restriction and the discharge end of the nozzle, the calibration determining the amount of air admitted to the fuel nozzle, and an air passage admitting air only to said orifice under normal running conditions and communicating with a re ion of higher air pressure than that maintained in the mixture passage.

2. A carburetor having in combination a throttle, a mixture passage with a fixed air entrance and a single fuel nozzle, having a restriction, and constituting the sole means for the introduction of the fuel supply on the inlet side of the throttle, a calibrated air inlet orifice of fixed area, provided through the wall of the fuel nozzle, an air passage admitting air only to said orifice under normal running conditions, said air passage constituting a well in which fuel stands when the engine isnot running, and an idling and starting by-pass, said calibrated orifice being of such size as to admita flow of fuel from said well to the nozzle insufficientto prime the engine for starting.

FREDERIG E. B-ALDJVIN; 

